1. Field of the Invention
The present invention relates to a method for producing a resin composition and a resin composition.
2. Description of the Related Art
Viscoelasticity is the property of materials that exhibit time-dependent strain upon the application of stress to the materials and return close to their original state with residual strain once the stress is removed. Viscoelastic resin compositions are used in various industrial sectors. Resin compositions suitable for resin binders for ink jet inks and electrophotography toners have a property of rapidly changing their viscoelasticity with an increase in temperature (hereinafter referred to as a “sharp melt property”) so as to satisfy both storage stability and image forming capability.
Crystalline polymers, such as polymers of a radical polymerizable monomer having a crystalline molecular chain and polyesters having a crystalline main chain, have the sharp melt property. Because of their significant low-temperature brittleness, however, crystalline polymers are difficult to use alone. Low-temperature brittleness characteristic of crystalline polymers is ameliorated in resin compositions containing both a crystalline polymer and an amorphous polymer as described in Japanese Patent Laid-Open No. 2012-88580.
A method for producing a resin composition according to Japanese Patent Laid-Open No. 2012-88580 involves at least a crystalline polymer synthesis process, an amorphous polymer synthesis process, and a process of mixing the crystalline polymer with the amorphous polymer. Such many production processes are not preferred in terms of environmental load.
Thus, there is a demand for a method for producing a resin composition that has a sharp melt property and has toughness at room temperature in a single production process.